Centrifugal spark control mechanism for flywheel magnetos



May 24, 1966 J. F. MARTIN v 3,252,351

CENTRIFUGAL SPARK CONTROL MECHANISM FOR FLYWHEEL MAGNETOS Filed Dec. 6, 1963 3 Sheets-Sheet 1 GE OF n V m VEMENT INVENT' JOHN F. MAETI J. F. MARTIN May 24, 1966 CENTRIFUGAL SPARK CONTROL MECHANISM FOR FLYWHEEL MAGNETOS Filed Dec. 6, 1963 3 Sheets-Sheet 2 INVENTOR Jo H N F MAETI N B AZ J. F. MARTIN 5 Sheets-s 5 May 1.96

Filed De 6' 1963 INVENTOR JOHN F. MAETN Z 4 3,252 351 CENTRIFUGAL SPARK JONTROL MECHANISM FOR FLYWHEEL MAGNETOS John F. Martin, Longmeadow, Mass., assignor to R. E.-

Phelon Company, Inc., a corporation of Massachusetts Filed Dec. 6, 1963, Ser. No. 328,734

' 8 Claims. (Cl. 74-568) This invention relates to flywheel magnetos and more particularly to the provision of a new and improved automatic spark advance mechanism for flywheel magnetos.

The provision in a flywheel magneto of means for providing automatic control of the spark in response to variations in engine speed is frequently a problem due to the unavailability of sulficient space for said means within the flywheel. This problem,- furthermore, is particularly acute in the very 'small flywheels of only a few inches in diameter. which are now in common usage. More specifically, in many flywheels, particularly in those of a very small diameter, the space within the flywheel isso crowded with the necessary magneto components that no space remains suflicient for the positioning and/01' swinging of governor weights of any substantial size. I

An object of the present invention is to provide a new and improved automatic spark advance mechanism for flywheel magnetos which comprises a governor weight or weights positioned external to the flywheel such that said weight or weights may be of any necessary size and yet be enabled to swing.

Another object of the present invention is to provide a new and improved automatic advance mechanism of the type set forth which is inexpensive and compact yet eflicient in operation.

Other objects and advantages of the invention will be apparent from the following description. It will be understood that changes may be made in the details of construction and arrangement of parts shown and described as the preferred form of the invention has been given by way of illustration only.

Referring to the drawings:

FIG. 1 is a longitudinal sectional view taken on line -11 of FIG. 2 looking in the direction of the arrows showing the details of construction of an embodiment of the invention; 1

FIG. 2 is a sectional side view of a device embodying the invention;

FIG. 3 is an end view of the device shown in FIG. 2;

FIG. 3a is a sectional view taken online 3a3a of FIG. 3 looking in the direction of the arrows;

FIG. 4 is a partially sectional end view of a form of the invention with an alternative construction;

FIG. 5 is a partially sectional end view of a form of the invention with another form of'alternative construction;

FIG. 6 is a sectional end view of another modified form of the invention; and

FIG. 7 is a side view of the form of invention shown in FIG. 6.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, and with particular reference to FIGS. 1 through 3a, the apparatus illustrated therein comprises a flywheel 10 of a flywheel magneto, and which is mounted upon the crankshaft or shaft 11.

'The automatic spark advance mechanism provided by the present invention for said flywheel magneto is positioned external to said magneto and includes said shaft 11, which is provided with a slot or groove 12 through said shaft and external to said magneto, and a housing or support 13 mounted for rotation on said shaft 11 adjacent to said slot or groove 12. Said housing 13 is Patented May 24, 1966 mounted on the shaft such that a range of movement exists between the shaft 1 1 and the housing '13. Towards this end, said housing is mounted on the shaft such that space 14 is provided adjacent to its mounting upon the shaft 11.

A permanent type magnet 15- is carried by said housing or support 13, said magnet being mounted for movement away from and toward the shaft 11 such that when said magnet is at its extreme inward position adjacent said shaft a retarded spark and additional voltage such as is desired, for example, for starting is provided by the magneto 10 and when said magnet is at its outward position an advanced spark is provided by said magneto. The range of movement of the magnet 15 between its outward and inward positions is governed or controlled or support 13 and the magnet .15 together, function as a weight which serves to draw support 13 and said magnet 15 to its outward position. The magnetic force or pull of said magnet to said shaft 11 serves to return the magnet 15 and support 13 to its inward position when said cen- ;trifugal force is reduced such as to be less than said magnetic force or 'pull.

A cam 16 is mountedv for limited rotation upon the shaft 11, said cam being operatively connected to the magnet 15 by means of the key 17 in the key slot '18 in- I the housing or support 13 and being adapted to be pivoted upon outward movement of the magnet 15 and housing 13 caused by centrifugal force.

A slot 19 is provided through the end of the housing 13 opposite to that carrying the magnet 15. Guide pin 20 is threaded into said slot 19 and extends into the slot or groove 12 through shaft 11 and operatively connects the housing 13 and said shaft. Said guide pin could be eliminated providing that alternative means are provided for accomplishing its functions. By way of specific example, said guide pin could be replaced by the provision of co-mating flat sides upon the shaft 11 and the housing 13.

Referring more particularly to FIGS. 4 through 7, such illustrate alternative forms of construction of the present invention.

With particular reference to the form of invention illustrated in FIG. 4, such comprises a permanent magnet 21 with the pair of pole shoes 22. In said form of invention, the housing 23 is discontinuous adjacent one side of the shaft 24, said discontinuous area containing a key 25 on the cam and which serves to operatively connect the cam '26 and the shaft :24. The shaft 24, furthermore, is substantially flat on its two opposite sides. The guide pin 20 is not utilized in this form of the invention. a

In the operation of the apparatus shown in FIG. 4, centrifugal force imparted to the housing 23 and the magnet 21 by the rotation thereof causes said magnet to pull away from the shaft 24 at a right angle thereto and this action through key 25 pivots the cam. The magnetic pull of said magnet 21 when said centrifugal force is re duced to a value lower than said centrifugal force serves to pull the magnet back adjacent the shaft 24.

FIG. 5 illustrates another modified form of the invention with another type of magnet 26 having two poles. The construction and operation of such form of this form of the invention is substantially similar to the FIG. 4

embodiment of said invention and will be apparent from i trate another modified form of the invention. The therein illustrated form of invention is generally similar to those shown in FIGS. 4 and 5 with the exception that, in the 'FIGS. 6 and 7 embodiment of the invention, the housing 23 is continuous about the shaft 24, the discontinuous area of the FIGS. 4 and 5 embodiments of the invention being connected by a connector portion 27 of said housing 2 3 and having an opening 27a for key 25 on the cam.

In FIGS. 6 and 7, furthermore, the form of magnet 28 utilized is similar to that employed in the embodiment of the invention illustrated in FIGS. 1 through'3a.

The operation of the device is believed to be apparent from the foregoing description taken in connection with the accompanying drawings.

From the foregoing, it will be seen that I have provided new and improved means for accomplishing all of the objects and advantages of the invention.

1 claim: 7

1. In a device of the character described, a shaft, a support mounted for rotation by said shaft, a magnet carried by and operatively connected to said support, said magnet and support being mounted for movement radially of said shaft by centrifugal force and toward said shaft by magnetic attraction of said magnet to said shaft, and a cam mounted for limited rotation on said shaft, said cam being operatively connected to said sup port and adapted to the rotated in opposite directions upon movement of said support and magnet due to centrifugal force and magnetic attraction of said magnet respectively.

2. In a device of the character described, a shaft, a support mounted for rotation by said shaft, a magnet carried -by and operatively connected to said support, said magnet being mounted for movement radially of said shaft by centrifugal force and toward said shaft by magnetic attraction, and a cam mounted for limited rotation on said shaft, said cam being operatively connected to said support and adapted to be pivoted in one direction upon movement of said support due to centrifugal force, and in the opposite direction upon movement of said support toward said shaft when the centrifugal force is less than the magnetic attraction of said magnet.

3. In a device of the character described, a shaft, a support mounted for rotationby said shaft, said support being slidably mounted on said shaft and adapted to be urged along said shaft by centrifugal force, a magnet carried by said support, and a cam mounted for limited rotation on said shaft, said cam being operatively connected to said support and adapted to be pivoted in one direction upon said movement of said support due to centrifugal force, and in the opposite direction by movement of said support and magnet towards said shaft by magnetic attraction of said magnet to said shaft.

4. In a device of the character described, a shaft, a support having a portion surrounding'said shaft and said support being mounted for rotation by said shaft, a

magnet carried by said support, said support being mounted for limited longitudinal movement radially of being mounted for sliding movement radially of and toward said shaft, a cam mounted for limited rotation on said shaft, and means operatively connecting said cam to said support and magnet such that movement of the magnet outwardly from said shaft by centrifugal force will pivot said cam, said magnet and support being returned toward said shaft by magnetic attraction of said magnet and shaft.

6. In a device of the character described, a shaft, a support mounted on said shaft and keyed to said shaft for sliding movement relative thereto, and for rotation by said shaft, a magnet carried by said support, said magnet being mounted on said support for movement radially of said shaft by centrifugal force and toward said shaft by magnetic attraction of said magnet to said shaft, a cam mounted for limited rotation on said shaft, and means on said cam engaging said support such that said cam will be pivoted by the actuation of said support by centrifugal force.

7. In a device of the character described, a shaft, a support mounted for sliding movement relative to said shaft and rotation by said shaft, a magnet carried by said support, said magnet and support being mounted for sliding movement radially of and toward said shaft, a cam mounted for limited rotation on said shaft, and means on said cam engaging said support such that said cam will be pivoted by the auctuation of said support and said magnet by centrifugal force. a

8. In a device of the character described, a shaft, a support mounted for rotation by said shaft, said support having a pin extending into an opening in said shaft for slidably mounting said support relative to said shaft, said support being urged radially of said shaft by centrifugal 2,863,320 12/1958 Mcndenhall 192-84 2,864,264 12/1958 Rass 74568 FOREIGN PATENTS 586,152 11/1959 Canada.

B'R-OUGHTON G. DURHAM, Primary Examiner.

W. S. RATLIFF, Assistant Examiner. 

1. IN A DEVICE OF THE CHARACTER DESCRIBED, A SHAFT, A SUPPORT MOUNTED FOR ROTATION BY SAID SHAFT, A MAGNET CARRIED BY AND OPERATIVELY CONNECTED TO SAID SUPPORT, SAID MAGNET AND SUPPORT BEING MOUNTED FOR MOVEMENT RADIALLY OF SAID SHAFT BY CENTRIFUGAL FORCE AND TOWARD SAID SHAFT BY MAGNETIC ATTRACTION OF SAID MAGNET TO SAID SHAFT, AND A CAM MOUNTED FOR LIMITED ROTATION ON SAID SHAFT, SAID CAM BEING OPERATIVELY CONNECTED TO SAID SUPPORT AND ADAPTED TO BE ROTATED IN OPPOSITE DIRECTIONS UPON MOVEMENT OF SAID SUPPORT AND MAGNET DUE TO CENTRIFUGAL FORCE AND MAGNETIC ATTRACTION OF SAID MAGNET RESPECTIVELY. 